Everyone agrees that being sedentary is bad and unhealthy and that being active is good and healthy. The research agrees, too; regular physical activity leads to good health, longer lives, and an improved ability to function throughout normal life. When you’re able to walk to the store, carry your groceries home, take the stairs, get out of bed without struggling, pack enough lean mass to survive a stay in the hospital, and ride your bike when you want to, you’re a functional human being, and remaining active on a regular basis helps maintain this state so crucial to basic health and happiness.

But what’s often hidden amidst the blanket pro-exercise sentiment is that too much exercise can have the opposite effect on health – people can really take physical activity too far. I talk about this all the time, so much that you’ve probably got “Chronic Cardio” emblazoned across your brain and shake your head when you see some hapless soul in spandex and the latest runners heaving himself down the street, heel first. I know just how bad that stuff can be, because I did it for a large part of my life. You’ve all heard that story before, though, about how even though training cardio hard gets you “fitter” in one sense of the word, it’s actually counterproductive for a healthy long life (doubly so if you want to have some lean muscle mass and pain-free joints in your later years).

We’ve seen hints in studies over the years:

One recent study found that in overweight sedentary subjects, moderate exercise was more efficient at helping them burn body fat – including a reduction that was far greater than what could be explained by the caloric expenditure – while intense exercise induced a “compensatory” response that hampered fat loss.

Another study examined weekly caloric expenditure via aerobic exercise in a group of former athletes and non-athletes and plotted it against mortality, cardiovascular disease, and hypertension. Death rate was highest in groups 1 and 2, the ones with the least amount of caloric expenditure, but group 6 (along with 1), which expended 2,500+ calories per week, had the highest rates of heart disease and high blood pressure. Those who exercised moderately lived the longest and were healthiest.

In a study on the exercise habits of college alumni and their impact on mortality, researchers found that up to 3,500 calories expended per week conferred a survival benefit, but at calorie expenditures greater than that, mortality began to tick upwards.

And in a pair of recent studies, researchers found that moderate exercise – jogging up to 20 miles a week at an 11 minute mile pace – offered the most protection against early mortality. Running more than 20 miles a week, or running at a 7 minute mile pace, offered fewer mortality benefits. In the second paper, Danish scientists found that people who spent one to two and a half hours jogging at a “slow or average pace” lived longer than those who didn’t run at all or who ran at a faster pace. James O’Keefe, a cardiologist and presenter at the Ancestral Health Symposium, was quoted as saying that “after about 45 to 60 minutes a day, you reach a point of diminishing returns.”

It’s pretty clear that once exercise gets to be “too much,” the benefits are reduced, or even reversed, and it becomes a chronic stressor that reduces overall wellness.

And so I thought it’d be helpful to give you guys a guideline for determining just how much is too much. This is a guideline I’ve had great success with, whether I’m training myself or clients: no more than 4,000 calories expended through focused exercise per week.

Is this a hard and fast rule? No, not exactly. Going somewhat above is probably okay.

Is it concretely established in numerous studies? There are hints toward its veracity in the literature, but nothing explicit. This is mostly stuff gleaned through experience (but the research does bear it out).

Does it apply to everyone, everywhere, whatever their goals may be? No. Someone training for the Hawaii Ironman Triathlon is going to require more if they hope to compete.

But as a general rule for the general population, it really does work well as a guideline. Burning 4,000 calories through focused exercise appears to be the cut off point (yeah, you could go a bit under or over, but the point is that we need to draw the line somewhere) after which health – including immune function and oxidative stress load – and quality of life – including free time, energy levels, and productivity – begin to take hits. Your performance may increase, and this might be worth it to you if your goals are primarily performance-oriented, but there’s a trade off. Keith Norris often writes about this idea, calling it the health-performance curve. I’m inclined to agree with him.

So – what does 4,000 calories worth of expenditure in a week look like, exactly?

Well, the simplest way I’ve found to describe it is in terms of road miles. If you’re doing 40 miles a week running or 80 miles a week cycling, you’re hitting roughly 4,000 calories. We don’t just run or bike, of course. We lift weights, we circuit train, we engage in metabolic conditioning, we row, we wrestle, we hike, we sprint, we box, we swim.

You could use an online calculator like FitDay or ExRx to get a better idea. For a 185 pound, 6 foot tall person to burn just around 4,000 calories a week, he could get away with:

That’s a pretty solid week of activity, I’d say, but it certainly isn’t excessive, and it would provide a far more well-rounded sense of fitness than just pounding away at the road for 40 miles. Feel free to use the (admittedly imperfect) tools linked above to figure out what your regular caloric expenditure looks like.

Not all activity “counts” toward your caloric expenditure. Taking a 30-minute stroll to the store doesn’t count as focused work. Taking a 60-minute hike up in the hills does. Going for a nice relaxing ride on the bike around the neighborhood doesn’t count, but doing twenty miles in a single day does. Carrying the groceries from the car to the house doesn’t count; carrying the groceries from the store to the house just might, though. “You know it when you see it” applies here, so use your better judgment.

I’d also suggest that expending your calories through a variety of activities is “better” than expending them through a single activity. As shown above, lifting weights, going for a run, biking a bit, and playing sports is more fun and probably less stressful than expending all your calories through running, which is veering into Chronic Cardio territory. A calorie (expended) is not a calorie (expended).

Look – exercise as often and as intensely as it pleases you. Just be aware that, in my opinion (having looked at the literature and drawn from my own experience training myself and others), 4,000 calories of focused work per week is the cut off point after which health and happiness begin to suffer for most people. If you’re an athlete whose only job is to train, and you’re privy to massages and cutting edge recovery techniques and everything else, then you’ll be able to handle more work. You’ll be far fitter than the average person and thus better equipped to mitigate the oxidative fallout from excessive exercise. But for members of the general population who have to contend with the day-to-day stress of living in this world, getting up early to feed the kids and beat traffic, balancing exercise time with work time with family time with personal time, sneaking peeks at the latest blog post, hoping to get enough sleep to make it through the next day? You’re going to have a harder time recovering from the stress of a 4,000+ caloric expenditure to make it worth your while.

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This entry was posted on Wednesday, October 10th, 2012 at 9:08 PM and posted in Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed.